A conventional dispenser for supplying a liquid for drinking is placed together with a carbon dioxide bottle or a barrel filled with the liquid for drinking, in a place other than customer's seats, for example, a kitchen or the like.
In the case that a shop tender receives an order from the customer in the seat, the shop tender walks to the place where the dispenser is placed, inputs an ordered number of a liquid for drinking to containers (steins or the like) via the dispenser, and carries the containers to the customer's seat.
When receiving an additional order from the customer, the shop tender temporarily returns to the place of the dispenser while holding the empty container, injects the liquid for drinking into a new stein after being washed at the place, and carries it to the customer's seat again.
In particular, when the orders of the customers are concentrated at the same time, a plurality of shop tenders have the dispenser in common, so that it is necessary that the shop tenders wait for the dispenser and it is hard to rapidly respond to the order.
On the other hand, the customer drinks the liquid for drinking which is delivered at a fixed time after the customer calls and places an order and cannot drink immediately when the customer wants to drink due to a waiting time.
Further, there is a case that the customer wants to order about half of the amount of the liquid for drinking in the container, however, normally, since the customer can only order a prescribed amount of injected liquid for drinking, the customer leaves part of the liquid for drinking, which is wasteful and uneconomical for the customer.
On the other hand, the customer holds back an order, and the shop cannot get turnover.
On the other hand, for the shop, it is necessary to provide a lot of shop tenders in order to rapidly respond to the orders of the customers so the labor cost is large for the shop.
Further, when settling the drinking money, there is a case that money trouble is generated between the customer and the shop side with regard to the cost demand because the customer has a small recognition about the drinking amount.
In order to solve the problem mentioned above, there has been developed a table in which a draft tower is placed as disclosed in Japanese Unexamined Utility Model Publication No. 4-115199.
In accordance with this invention, the draft tower for discharging beer is placed in a customer's seat table and the discharge amount from the draft tower is measured so as to be displayed in integrating meters provided in positions near the customer's seat and a cash register of the shop.
Accordingly, it is not necessary to order the shop tender at a time of placing an order for the liquid for drinking, and the customer can immediately discharge a necessary amount of liquid for drinking at a time when the customer wants to drink.
Further, the customer cannot only enjoy the operation of discharging the liquid for drinking, but also can have the liquid for drinking while confirming the discharge amount (drinking cost) by himself or herself. Accordingly, the customer has a sense of security. Further, since the customer can confirm the drinking amount by himself or herself, it is possible to prevent trouble with respect to money.
Further, for the shop side, it is not necessary to prepare new washed containers, it is unnecessary to provide the shop tenders, and the cost is extremely efficient.
However, for a flow meter in the conventional draft tower, a so-called axial flow type meter in which an axis of impeller is set in parallel to a flow is employed because its principle and structure are simple and the cost is advantageous.
In other words, the flow meter utilizes the principle that the impeller rotates at a speed in proportion to the flow speed of the fluid obtained by arranging the axis of the impeller in parallel to the fluid flowing within a flow passage, and determines the flow rate by detecting a rotational speed.
However, in the conventional flow meter mentioned above, since the flow meter utilizes a physical rotation caused by the impeller, there is a problem when the flow meter measures the liquid for drinking containing the carbon dioxide gas such as beer or the like, the impeller is rotated in the same manner even at a time when the liquid-cut state is formed and the flow passage is in a bubble or gas state, and the flow meter erroneously counts.
In the draft tower placed in the table of the customer's seat, since the charge is left up to the customer, it is necessary to extremely accurately measure the injection amount of the liquid for drinking.
In the case that the liquid amount is counted and the liquid for drinking is not actually injected although the customer injects, confidence in the shop deteriorates.
On the basis of the matter mentioned above, there has been desired a draft tower which can accurately measure a liquid amount of the liquid for drinking.